FIG. 9 is a side view showing the appearance of a typical hydraulic power shovel applied to general use, including an operator cabin 1, an upper turning body 2, an upper turning body frame 2a, and a lower traveling body 3.
FIG. 10 is a longitudinal section showing the relation of placement between the operator cabin 1 and the upper turning body frame 2a, in which a floor plate 21a of the operator cabin 1 is mounted by a shock absorbing device 24 to a supporting frame 22b to which the upper turning body frame 2a is welded.
FIG. 12 is a longitudinal section showing the detail of the related connection between the floor plate 21a, the supporting frame 22b, and the shock absorbing device 24. In FIG. 12, a resilient member 24a, which fills up a case 24c, arranged between the floor plate 21a and the supporting frame 22b, and a resilient member 24b, which fills up a case 24d, sandwich the supporting frame 22b therebetween. A floor boss 21b welded on the floor plate 21a penetrates the case 24c, the resilient member 24a, the case 24d, and the resilient member 24b, and a bolt 26 is fastened to the floor boss 21b, so that a predetermined distance is provided between the resilient members 24a and 24b for tightening the floor plate 21a and the supporting frame 22b during assembly. Also, a bracket 21c, which is welded on the frame of the operator cabin 1, is fastened to the floor plate 21a by a bolt 27.
In this manner, as shown in FIG. 11, four shock absorbing devices 24 are placed in both corners of the front and back ends of the operator cabin 1. Resilient members 25 are placed between the periphery of the floor boss 21b and the periphery of the holes in the supporting frames 22b through which the floor boss 21b extends, so that the horizontal surface of the operator cabin 1 can be resiliently located against the upper turning body frame 2a. However, in the prior art mentioned above, since the floor plate 21a of the operator cabin 1 is connected to the supporting frame 22b of the upper turning body 2 by the four shock absorbing devices 24, the number of natural vibrations of the operator cabin 1 becomes small, whereby the number of natural vibrations of the operator cabin 1 during high speed running of a hydraulic power shovel becomes close to the gear engaging frequencies provided by a caterpillar track and a sprocket wheel, so that the operator cabin 1 resonates therewith. For this reason, the vibration of the operator cabin 1 is increased, especially the rolling from side to side is increased. While the main object of the above-mentioned prior art is to provide shock absorbing effects by the shock absorbing devices 24, damping effects against increased vibrations produced by resonance of the operator cabin 1 are not effective, thus deteriorating the riding comfort for an operator during high speed running as well as the mechanical strength of the operator cabin 1.
Therefore, an object of the present invention is to solve the above-mentioned problems and provide the resilient supporting construction of the operator cabin 1 against the vehicle body to reduce vibrations, particularly during high speed running of the hydraulic power shovel, and prevent trailing turns of resilient members during assembly of the shock absorbing devices 24.